Bear-trap dam.



A. LUTZ & J. HUBER.-

BEAR TRAP DAM.

APPLICATION FILED FEB. 24, I915.

Patented July 17, 1917.

BEAR-TRAP DAM.

To all whom it may concern:

Be it known that we, ALois LU'rz, a citizen, of Austria, and J AKOB HUBER, a citizen of Switzerland, residing at Zurich, Switzerland, have invented certain new and useful Improvements in Bear-Trap Dams; and We do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

Our invention relates to improvements in bear-trap dams, and has for its object to improve the structure of such dams so that they may be more easily operated.

According to our invention the two leaves of the dam at their contacting point have sliding contact over an arched or curved portion, so that the pressure at the contact portions of the two leaves is so directed that the proper turning moment with respect to the hinge points of the leaves will be such as to give the desired movements to the leaves.

This structure permits the use of a much smaller angle between the leaves when in raised position; consequently a narrower width of base between the hinge points, and shorter leaves are possible, with a resulting decrease in the cost of construction.

The curved guide-way may be on either leaf.

Referring to the drawings, in which like parts are similarly designated Figure 1 is a vertical transverse section of a bear-trap dam embodying our invention.

Fig. 2 is a plan view thereof.

Fig. 1 is a view similar to Fig. 1, showing the curved guide way on the upstream leaf. 1

Fig. 3 is a vertical transverse section of a modification.

In the drawings, a is the up-stream water, or dominant pool, whose damming element 1 is hinged at 3 to a suitable foundation. The upstream leaf has a flange or portion 8 that engages and slides on the curved portion 9 of the down stream leaf 2. This down-stream leaf 2 is mounted to swing on a horizontal axis or hinge 4:, similar to the hinge 3, and said hinge 4 is likewise secured Specification of Letters Patent.

Patented July 17, 1917.

Application filed February 24, 1915. Serial No. 10,224.

to the necessary masonry or concrete foundation. 4

The chamber 5 is formed in the anglebetween the two leaves 1 and'2 of the dam.

Water is conducted .to this chamber 5 from the upstream side of the dam or dominant pool a by a conduit f, which communicates with the pool at c and with an open pit .7) which has a discharge opening into chamber 5 as indicated at d.

The pit 6 also discharges through a conduit 9 into the down-stream water at c, and each conduit is provided with a valve or gate, indicated at 6 and 7. By closing gate 7 and opening gate 6, water from the dominant pool a is admitted through conduit 7' and pit b intothe chamber 5 and lifts the dam to the position shown in full lines in Fig. 1. By closing gate 6, and opening gate 7, the water in chamber 5 is discharged through the conduit 9 into the down stream portion of the stream at e and the leaves drop to the position shown in dotted lines in'Fig. 1. V

The up-stream leaf 1 engages with its flange 8, which is approximately at right angles tosaid leaf, on the arched surface 9 of the down-stream leaf, and slides thereon during the simultaneous movement of the two leaves, thereby preventing any opening of the leaves at the apex or top of the dam, so that no special cover plates are required.

The curved guide 9 is so formed that the load at the meeting line of the two leaves has such a leverage with respect to the two hinge points 3 and 4, that with ;a normal water level in the dominant pool and a constant pressure in chamber 5, the leaves will be balanced.

In order to maintain a constant pressure in the chamber 5 when the leaves are in raised position, the pit 6 between the two valves 6 and is connected to an overflow opening 10, discharging down-stream, and thus the normal dominant pool level is maintained under ordinary conditions of water supply.

It will thus be seen that the height of the crown of the dam will automatically vary with the level of the water at the overflow.

A rise of the level of the dominant pool causes a greater volume of water to flow over the crown of the leaves, forcing the latter into a lower position so that the normal level of the pool will be again established provided the level of the down stream remains unchanged which will be the case if the river bottom has suflicient slope to carry off the additional overflow.

If the overflow is too great and the down stream rises and increases the outside pressure on the down stream leaf the water level of the up stream will sink below normal. However, this lowering of the leaves by the increased outside pressure, may be prevented by increasing'the pressure inside the chamber 5 by raising the crown of the overflow 10, which crown is formed by the upper edge of a gate 11.

The position of the crown of the overflow 10 can be controlled automatically (as shown in Fig. 3) by connecting the gate 11 to the up stream leaf 1 through a lever 12 or similar device. I It will be seen that as the leaves move down the gate is raised and vice versa. When theleaves are in their-lowest positions the gate will be in its raised position as indicated by dotted lines Fig. 3.

We'claim: V

1. In a bear trap dam, two oppositely movable leaves, one of said leaves having a bent bearing portion extending below the I plane-of the leaf, the other leaf resting on said bearing portion suhstantlally throughout the extent of movement of the leaves.

2. In a bear trap dam, two oppositely movable leaves, a bearing portion on one of said leaves bent below the plane of the leaf, and a flange on the other leaf slidable Gopies of this patent may be obtained for .on said bearing portion substantially them, a bent bearing surface on the free end of the down stream leaf extending below the longitudinal plane thereof, and a downwardly directed flange on the free end of the up-stream leaf bearing on said bent portion substantially throughout the extent of movement of said leaves.

et. In a bear trap dam, two oppositely movable pivoted leaves forming a chamber between them, a bent portion formed on the free end of the down-stream leaf extending below the plane of the latter, a flange on the free end of the up-stream leaf extending below the plane of the latter and hearing on said bent portion substantially throughout the extent of movement of the leaves, an overflow communicating with the chamber and the down stream water,

a movable crown for the overflow, and

means to automatically change the position of the crown in unison with the movement of the leaves.

In testimony that we claim the foregoing as our invention, we have signed our names in presence of two subscribing witnesses.

ALOIS LUTZ. JAKOB HUBER.

Witnesses WILH. REINI-IARD, CARL Gunman.

five cents each, by addressing the Gommissioner of Patents. Washington, D. G. 

